DE19753261A1 - AC machine esp transverse flux type - Google Patents

Abstract

The AC transverse flux machine has a rotor (2), with a stator (3) arranged in a basic body (19) with at least one cooling unit, assigned to the stator. The rotor and stator form in a radial direction, at least respectively an inner (28,33) and an outer intermediate space (34,35). Facilities are provided for the filling of at least a part region of the intermediate spaces (28,33,34,35) with a cooling medium. The facilities for filling at least one part region of the intermediate spaces between the rotor and the stator, include at least one duct in the basic body (19) and at least one duct couplable indirectly with a cooling medium supply unit.

Description

The invention relates to a method for cooling an AC machine, in particular a transverse flux machine or a rotating field machine, also an AC machine.

Electrical machines in the form of AC machines are in various designs known from a variety of publications. AC machines, for example asynchronous machines or Synchronous machines that work on the principle of rotary field generation, are from Dubbel, paperback for mechanical engineering, page V18-V31, known.

AC machines that work on the transverse flow principle are, for example, in the following publications

• (1) DE 35 36 538 A1
• (2) DE 37 05 089 C1
• (3) DE 39 04 516 C1
• (4) DE 41 25 779 C1
  disclosed. These essentially describe the basic principle and the structure.

AC machines that work on the transverse flow principle, comprise at least one stator with at least one armature winding and a rotor opposite the armature winding. The rotor is there from at least two side by side, by an intermediate layer made of magnetically and electrically non-conductive material, Ring elements in the circumferential direction a variety of alternately  have arranged polarized magnets and soft iron elements. Such an arrangement of two ring elements forms a pole structure. Transverse flux machines are preferably constructed symmetrically. This then comprise two separated by a central carrier disc Pole structures.

In such a machine is in operation both in the rotor and in Stator due to those occurring through the windings and the magnetic cores and heat losses due to induced eddy currents generated. If appropriate measures are not taken, this limits the Resilience, the duration of loading and thus also the usability of the AC machine. In particular, situations are particularly critical such a machine at high load and above all high speed is working.

In order to avoid this disadvantageous effect, it is generally known that Connect stator to cooling devices. In this way, a Heating of the machine and its components can be reduced.

DE 43 35 848 A1 discloses a large number of possibilities for Improvement of the cooling effect is known, in particular a cooling arrangement perform such that the cooling devices at least one cooling channel have, which in the area or near the carrier disc in the Stator installed and can be flowed through by a cooling fluid. Every cooling channel is only minimal from the carrier disc by a channel cover Thickness and the air gap between the rotor and stator separated.

Also known from this document is an axial version running cooling channel in a spacer, which is between a pair of stator sections is provided. The spacer is the Carrier disc radially opposite, is symmetrical to the carrier disc  arranged and thermally insulated from the stator sections. This is made of a material that is magnetically passive and a good one Has thermal conductivity.

Another known way to increase heat reduction consists of the carrier disc and that in the area of the cooling channels opposite areas of the stator with interlocking to provide complementary teeth which are substantially parallel have mutually extending surfaces and an air gap from each other are separated.

Furthermore, it is known, either instead of the one described above Measures or additionally to use a rotor, which on the Carrier disk attached, has at least one pair of collector rings, which by an insulating ring made of magnetically passive and electrically not conductive material are connected, and in which in the insulating ring, in Distributed circumferential direction, memory cells are incorporated with a Phase transition material are filled.

The effect of these known measures can be determined by a suitable one Material selection and surface treatment can be increased.

The disadvantage of the known designs is that large Cooling effects can only be achieved with a high manufacturing expenditure can. The most stressed and heated areas of the rotor can often not be optimally and above all not evenly cooled. Due to the construction of the transverse flux machine, the cooling is some Areas of the rotor only possible indirectly, especially the Junctions between the individual ring elements of a pole structure and / or the connection between the carrier disk and the pole structures. This  however, are the areas most exposed to warming are.

In induction machines, especially asynchronous machines, which also are made up of rotor and stator, the stator preferably on considered a larger diameter in the radial direction than the rotor is arranged, the rotor evades intensive cooling, if not externally a cooling gas, for example air or nitrogen, or a Liquid such as water or oil can be supplied. It is generally known that with traction drives with greater performance So far, induction machines have prevailed. At Smaller sizes thus remain the cooling of the rotor and thus the Stator winding head unsatisfactory. To solve this problem proposed to improve the movement of air in the forehead area and a internal air circuit between the stator core and the rotor core realize to improve cooling. With this solution, only the in air trapped in the electrical machine moves. Heat content and However, heat transfer does not lead to any noticeable improvement.

The invention has for its object a general cooling arrangement for run an AC machine such that in addition to the Ensuring effective cooling of the AC machine, especially the rotor as a particularly heavily stressed component less constructive and costly effort is recorded.

The solution according to the invention is characterized by the features of claims 1, 2 and 7 characterized. Advantageous configurations are in the Subclaims described.

For versions of AC machines with one rotor and one Stator, which each have at least one radially inner and / or  form radially outer space with each other, in particular Transversal flux machines, in which devices for cooling the stator are provided according to the invention, the ones that cannot be directly cooled Areas of the rotor by means of an atomization Coolant-air mixture cooled. To do this, the AC machine, especially the transverse flux machine partially filled so that at least in the installation position below the rotor axis in the mathematical sense forms a coolant sump in non-operation such that when the AC machine through the rotor rotation partially the coolant entrained and atomized and the atomized particles in at least one of the gaps and thus get into the area of the rotor. The filling is preferably carried out in such a way that in the radially outer direction also as Air gap designated clearance between rotor and Stator viewed below the rotor axis in a mathematical sense Forms coolant sump. In the operation of the alternating current machine that becomes Coolant entrained by the rotor rotation and due to it atomizes the forces acting on the coolant. It essentially arises in Dependence on the speed of the rotor shaft and the filling level Coolant-air mixture in the air gap between the rotor and stator. This takes over the heat transport through heat flow and heat transfer from the rotor to the water-cooled stator, for example. The coolant Air mixture essentially takes over only the heat transport, which is why no additional devices for cooling the coolant are provided have to be and a one-time partial filling with coolant, which in the Inside the AC machine is sufficient.

The gaps between the rotor and the stator are regarding their radial position based on the theoretical symmetry or Axis defines which corresponds to the axis of rotation of the rotor.  

Preferably, as a low viscosity coolant, i.e. H. with a low internal friction due to force effects between the Molecules used, for example in the form of low-viscosity oil.

The solution according to the invention offers the possibility of dissipating heat also in the critical areas, which by means of conventional Cooling arrangements have so far been insufficiently cooled. At the same time, the use of oil also offers the possibility of Corrosion protection of the rotor.

Preferably in AC machines with a radially inside and a radially outer space between the rotor and stator a partial filling selected, which when the AC machine is not in operation enables a coolant level at a height that is in the area of the of the gaps located radially on the inside in relation to the rotor axis lies between the rotor and the stator. These spaces are also called Called air gaps. It is filled with a higher coolant level also conceivable.

The solution according to the invention is for AC machines different structures applicable. This is therefore both at AC machines operating on the transverse flow principle, as well AC machines that work on the rotating field principle can be used. Furthermore, the applicability is independent of the structure and thus especially in transverse flux machines with essentially symmetrical structure, d. H. with a rotor with both sides of one central support plate in the axial direction extending pole structures as Can also be used for versions with only one pole structure.

Also, two need not necessarily be one above the other in the radial direction arranged air gaps are provided, one is sufficient, d. H. either a radially outer air gap or a radially inner air gap. Is crucial  only that the coolant level is at least in the area of the rotor, the rotor also with a partial area in the circumferential direction completely in can immerse the coolant sump.

This option can be used as a measure for additional cooling Combination with conventional cooling measures for every type of AC machines are used. For machines with less Performance is then also partial filling in combination with a simple stator cooling sufficient.

The selection of the suitable combinations of the invention Oil mist cooling with conventional cooling arrangements for stator cooling at the discretion of the specialist and depends on the specific Use case.

The stator can be cooled in different ways, directly or indirectly using different cooling media. In the simplest case is this connected to corresponding cooling devices or is it Coolant channels that can be filled with coolant are provided in the stator main body.

In addition, however, there is the possibility of cooling the Rotor with already known measures for cooling the rotor, especially to combine for local cooling of rotor sections.

Here are some examples:

• - For example, it is conceivable in the stator near the carrier disk to provide at least one cooling channel which is provided by a cooling fluid can be flowed through, the cooling channel only from the carrier disk through a channel cover of minimal thickness and the space is separated between the rotor and stator.  
• - In a special embodiment, the cooling channel can run axially and be installed in a spacer between one A pair of stator sections is arranged. The spacer is symmetrically in the radial direction opposite the carrier disc arranged and thermally insulated from the stator sections. The spacer is preferably made of a material which is magnetically passive and has good thermal conductivity. she points essentially radially on both sides of the cooling channel running wide cavities on which a thermal Form insulation from the neighboring areas of the stator. The cavities can be covered with air or other insulation materials be filled.
• - Furthermore, the cooling channel in the base body of the stator be arranged.
• - An embodiment is conceivable in which the carrier disk and the in the area of the cooling channels opposite areas of the stator to be provided with mutually complementary teeth, which in have substantially parallel surfaces and are separated from each other by an air gap.
• - Instead of or in addition to the examples listed above, the design of the rotor is modified such that the rotor attached to the carrier disk has at least one pole structure, in which the annular arrangements of alternately magnetizable magnets and soft iron elements by an insulating ring made of magnetically passive and electrically non-conductive Material are connected. In this insulating ring, memory cells are incorporated in the circumferential direction, which are filled with phase change material, the melting point of which is below a predetermined temperature.
  With regard to further possible measures, reference is made to DE 43 35 848 A1, the disclosure content of which for possible combinations of the solution according to the invention with known cooling arrangements is to be included in full in this application.

In terms of device, it is only necessary to assign the AC machine only means for realizing the partial filling. The partial filling may change

• 1) solely on the spaces between the rotor and stator or rotor and stator body or
• 2) generally on the stator mounted in the stator body enclosing stator housing or
• 3) cover the spaces between the rotor and housing.

The first option is used especially for versions of AC machines, especially in transverse flux machines preferred, which additional cooling devices on the stator body exhibit.

In the second option, a coolant sump forms when partially filled in the housing in which the stator body is immersed. Then there are Possibilities to provide that coolant from the housing in the To let spaces pass. For example, this is conceivable Through openings in the stator body, which the interior of the housing with connect the gaps.  

The simplest way of realizing partial filling is to use the Form coolant sump such that the stator in this area completely immersed and thus also the radially outer space between the stator and rotor is partially filled. In a preferred one Execution is also carried out here in such a way that the rotor for Immersed part in the coolant sump. The partial immersion of the rotor offers the advantage that even at low speeds corresponding cooling effect can be achieved, while with the provision of Coolant sump level at a short distance from the outer circumference of the The cooling effect only sets in at an increased speed.

The stator is partially submerged at least partially below the theoretical Rotor axis in the coolant sump, this is preferably with corresponding channels provided, which in cooperation with other, in In addition, the rotor provided channels with a so-called inner circuit form for liquid mist cooling. The corresponding channels are included in the rotor preferably in the immediate area of the outer circumference of the Rotors arranged and preferably extend in some form about the axial extent of the rotor. The inner cycle offers that Advantage, the coolant viewed in the axial direction from one side to the other end of the stator or the rotor and at the same time additional rotor cooling due to the internal circuit enable.

The achievement of the object is described below with reference to Figures explained.

Show it:

Fig. 1 a detail of a sectional view of a transverse flux machine according to the invention with partial load;

Fig. 2-5 additional suitable for combination with the partial filling possibilities for rotor cooling,

Fig. 6 is a simplified representation of an axial section of a three-phase asynchronous machine with partial filling according to the invention.

Fig. 1 illustrates in a sectional view the structure of an AC machine in the form of a transverse flux machine 1 in the installed position. This comprises a rotor 2 and a stator 3 . The rotor 2 comprises a shaft supported in a stator 4 rotor shaft 5 with a non-rotatably mounted thereon and extending substantially in a radial direction central support plate 6 on both sides in each case coaxially arranged at the end faces of the rotor axis of rotation A pole structures - a first pole structure 7 and a second pole structure 8 are provided. Each pole structure 7 and 8 comprises two juxtaposed in the axial direction and in each case by an intermediate layer 9 and 10 of magnetically and electrically non-conductive material separate rows 11 and 12 or 13 and 14 alternately magnetized in the circumferential direction of magnets with intervening soft iron elements sixteenth In the case shown, each pole structure 7 or 8 is assigned an end ring 17 or 18 at the end .

The stator 3 has a base body 19 , in which radially outer and radially inner armature windings 21 or 23 and 20 or 22 are accommodated which extend in the circumferential direction. These are surrounded by axially running cutting band cores 24 , 25 or 26 and 27 . The armature windings 20 and 22 form an inner stator part 28 and 29 with the associated cutting band cores 24 and 26 relative to the installation position in the radial direction, the armature windings 21 and 23 each form an outer stator part 30 and 31 with the cutting band cores 25 and 27 .

The inner diameter d _i and the outer diameter d _{a of} the rotor 2 are selected for the dimensions of the stator parts 28 and 29 or 30 and 31 such that spaces are also formed between the rotor and the stator, which are referred to as air gaps. A first space between the inner stator part 28 and the rotor 2 , a second space 33 between the inner stator part 29 and a third and fourth space 34 and 35 are each formed between the outer stator parts 30 and 31 and the rotor 2 .

The transverse flux machine here is assigned means for filling with an operating medium, which are not shown in detail here. The filling takes place at least over part of the outer spaces 34 and 35 in the radial direction. Preferably, however, a fill level of the coolant sump is selected in the region of the radial expansion of the inner intermediate space when not in use, as shown in FIG. 1. It is conceivable to fill only the gaps, ie the area between the rotor 2 and the base body 19 . However, it is also possible to immerse a part of the base body 19 in a coolant sump, connections to the interspaces having to be made in each case. This latter case also offers the possibility of simplified stator cooling.

When the AC machine, in particular the transverse flux machine, is started up, the coolant is entrained by the rotor rotation and atomized on account of the forces acting on the coolant as a result. Basically, depending on the speed of the rotor shaft and the filling level, a coolant-air mixture is created in the spaces 32 to 35 between the rotor 2 and the stator 3 . Through heat flow and heat transfer, this takes over the heat transfer from the rotor 2 to the water-cooled stator, for example. The coolant-air mixture essentially only takes on the heat transport, which is why no additional devices for cooling the coolant need to be provided and a one-time partial filling with coolant, which remains inside the AC machine, is sufficient.

For direct cooling of the stator 3 , cooling channels 37 , 38 , 39 and 40 are provided, through which a cooling liquid can flow.

Possibilities for additional cooling of the rotor 2 are described in FIGS. 2 to 5. These can be combined with the partial filling according to the invention. The same reference numerals are used for the same elements.

FIG. 2 illustrates one possibility on the basis of a detail from FIG. 1. This figure shows a spacer 42 which is arranged on the radially outer side of the base body 19 between the two stator parts 30 and 31 and is fastened to the base body 19 with casting compound 43 . In its radially inner area, the spacer disk 42 has a wide-area cooling channel 44 , which is separated from the opposite area of the carrier disk 6 only by the wall 45 of a channel cover 45 . In this way, heat can be extracted from the carrier disc 6 in this area over the entire axial width of the spacer in the circumferential direction, the carrier disc 6 preferably consisting of a material with very good thermal conductivity.

A preferred embodiment consists in providing thermal insulation 47 with respect to the adjacent stator regions. This can be formed, for example, by a cavity.

As an alternative or in addition to the cooling duct 44 according to FIG. 2, there is the possibility of providing a radially extending, broad-area cooling duct 46 which is opposite a corresponding area of the carrier disk 6 of the rotor 2 . Here, the cooling duct 46 is located in an area with a small distance from the rotor shaft 5 . In addition, the cooling effect can be supported by the fact that on the carrier disc 6 and the base body 19 have complementary interlocking teeth 48 and 49 , which are assigned to one another without contact and are separated from one another at all times by an air gap.

Another special design of a rotor 2 for an AC machine is shown in FIGS. 4 and 5.

Fig. 4 illustrates a detail of a sectional view through a rotor 2. The carrier disk 6 and the pole structure 8 are shown with the two rows 10 and 11, which are separated from one another by an intermediate layer 9 but are mechanically connected to one another. As shown in FIG. 5 in a view A corresponding to FIG. 4, the intermediate layer 9 contains a multiplicity of memory cells 49 arranged distributed over the circumference. These storage cells contain a phase transition material whose melting point or boiling point is below a predetermined temperature. In practice, this predetermined temperature is expediently chosen so that it is below the critical temperature of the permanent magnets which are embedded in the pole structures.

Fig. 6 illustrates in a schematically simplified view of an axial section of an alternator in the form of a three-phase asynchronous machine with the inventive partial load. The three-phase asynchronous machine comprises a stator 51 and a rotor 52 , the stator 51 at least partially enclosing the rotor 52 in the circumferential direction with the formation of a space 53 . The stator 51 , which is also called the primary part, comprises a three-phase winding 54 , while the rotor 52 is provided with a so-called short-circuit winding 55 . The power is transferred to the asynchronously rotating rotor 52 by means of the rotating field generated in the stator. Stator 51 and rotor 52 are arranged in a housing 56 . In the installed position below the theoretical rotor axis A _{R theoretically} , which at the same time corresponds to the axis of rotation of the rotor, a coolant sump 57 is formed by partial filling when not in operation. The coolant sump 57 extends, viewed in the axial direction, from a so-called front end space 58 to a rear end space 59 . The coolant sump mirror 60 in non-operation is preferably provided in the region of the outer periphery 61 of the rotor, wherein preferably the rotor 52 is immersed in the non-operation into the coolant sump 57 partly. The stator 51 is also, viewed in the installed position, surrounded by coolant below the rotor axis A _R theoretically, and the intermediate space 53 below the theoretical rotor axis A _{R theoretically} is also filled with coolant over a part in the circumferential direction. During the operation of the asynchronous machine, ie when the rotor 52 rotates, the coolant is entrained from the coolant sump 57 and atomized in the intermediate space 53 . A liquid mist is thus formed both in the intermediate space 53 and in the end regions 58 and 59 , which are formed by the end sides of the rotor 52 , stator 51 and housing 56 , which, as already for the embodiment according to FIG Fig. 1 sufficiently described, fulfilled, from. Furthermore, in the present embodiment, additional channels are provided in the rotor and in the stator, which are denoted here by 62 and 63 . The channels 62 arranged in the stator 51 are preferably arranged in the area of the outer circumference 64 of the stator 51 . These extend from one end face to the opposite end face of the stator 51 in the installed position. The length of the channels, their design and their management are at the discretion of the specialist. However, a channel guide is preferably sought which describes a minimum length between the two end faces. At least one channel 62 is to be provided in the stator 51 . A plurality of channels 63 arranged distributed in the circumferential direction are provided in the rotor 52 . A plurality of channels 63 are preferably arranged on a common diameter in relation to the theoretical rotor axis A _R theoretically. These channels 63 also extend over the entire axial extent of the rotor 52 between the two end faces of the rotor. Here too, the design, in terms of size, _shape and distance from the theoretical rotor axis A, is _at the discretion of the _{person skilled} in the art. Because of the rotor rotation, a so-called inner circuit is formed between the channels 62 and 63 depending on the direction of rotation of the rotor 52 , which transports liquid from the coolant sump 57 through the channels 52 in the stator 51 and the channels 63 in the rotor 52 and leads it in the circuit . This effect creates an additional cooling option for the rotor. It is possible to use asynchronous machines which are already available and which contain appropriate bores in the rotor and stator for the purpose of cooling and which use these to implement an internal air circuit without changing these channels for the internal coolant circuit.

The method according to the invention is not applicable in terms of its applicability to a specific mode of operation of the AC machine and one certain structure limited. It is only necessary to ensure that in A coolant sump is present in the area of the outer circumference of the rotor, from which due to the rotor rotation coolant or coolant carried away and thus atomized.

Claims (13)

1. A method for cooling an alternating current machine with a rotor and a stator, which each form at least one radially inner and / or one radially outer intermediate space;

• 1.1 in which at least a portion of the stator is cooled;
• 1.2 in which the AC machine is additionally partially filled with a coolant in such a way that
  • 1.2.1 a coolant sump is formed in the non-operating position in the installed position, the mirror of which adjusts itself at least in the area of the outer intermediate space between the rotor and the stator or rotor below the axis of symmetry of the alternating current machine and
  • 1.2.2 the coolant is atomized in the intermediate space during operation of the AC machine by the rotor rotation.

2. The method according to claim 1, characterized in that the mirror of the coolant in the area of the radially inner space between rotor and stator. 3. The method according to any one of claims 1 to 2, characterized in that that only the space between one carrying the stator Base body, the stator and the rotor is filled. 4. The method according to any one of claims 1 to 3, characterized in that a housing enclosing the stator, the interior of which the spaces formed between the rotor and stator coupled is filled and the coolant in the space between the rotor and Stator is directed.   5. A method for cooling an AC machine with a rotor and stator arranged in a housing, the rotor with the stator and the rotor with the housing each forming at least one intermediate space with one another;

• 5.1 in which at least a portion of the stator is cooled;
• 5.2 in which the alternating current machine is additionally partially filled with a coolant in such a way that
  • 5.2.1 a coolant sump is formed in the non-operating position in the installed position, the mirror of which adjusts itself at least in the area of the space between the rotor and housing below the axis of symmetry of the AC machine and
  • 5.2.2 when the AC machine is operated, the coolant is atomized in the intermediate space by the rotor rotation.

6. The method according to any one of claims 1 to 6, characterized in that an oil with a low viscosity is used as the cooling liquid. 7. AC machine, especially transverse flux machine

• 7.1 with a rotor;
• 7.2 with a stator;
• 7.3 with at least one cooling device which is assigned to the stator;
• 7.4 rotor and stator and / or rotor and housing form at least one inner and one outer space in the radial direction;
  characterized by the following characteristic:
• 7.5 means are provided for filling at least a partial area of the intermediate spaces with a coolant.

8. AC machine according to claim 7, characterized in that that the means for filling at least a portion of the Gaps between rotor and stator and / or rotor and  Housing at least one in one coupled to the stator Basic body and this provided and at least indirectly with a coolant supply device can be coupled channel. 9. AC machine according to claim 8, characterized by the following features:

• 9.1 with a housing enclosing the base body;
• 9.2 the means for filling the intermediate spaces comprise a feed channel connected to the interior of the housing and closable and connectable to a coolant device;
• 9.3 the feed channel is coupled to the channel provided in the base body via the interior of the housing.

10. AC machine according to one of claims 7 to 9, characterized characterized in that the cooling device associated with the stator at least one fillable with a cooling medium and in Base body arranged channel includes. 11. AC machine according to one of claims 7 to 10 characterized by the following features:

• 11.1 the rotor comprises a carrier disk and at least one pole structure which extends in the axial direction away from the carrier disk and is arranged thereon;
• 11.2 there is at least one cooling channel in the base body in the vicinity of the carrier disk, through which a cooling medium can flow;
• 11.3 each cooling channel is separated from the carrier disc only by a channel cover of minimal thickness and the space between the rotor and stator.

12. AC machine according to one of claims 7 to 11, characterized characterized in that the carrier disc and in the area of Areas of the stator located opposite cooling channels interlocking complementary through an air gap separate teeth are provided. 13. AC machine according to one of claims 7 to 12, characterized by the following features:

• 13.1 each pole structure comprises two rows of juxtaposed rows of magnets, alternately magnetized in the circumferential direction, with an intermediate layer made of magnetically and electrically non-conductive material (intermediate ring);
• 13.2 memory cells are incorporated into the intermediate layer, distributed in the circumferential direction, which are filled with a phase change material.